Green Manure Crops Affected Soil Chemical Properties and Fungal Diversity and Community of Apple Orchard in the Loess Plateau of China

The present study aimed to clarify the effects of three manure crops in orchards on nutrients and fungal community diversity and composition of the soil in the Loess Plateau. The high-throughput sequencing technology was used to analyze the fungal community diversity and composition in an apple orchard intercropping three types of green manure in the Loess Plateau of China. At the same time, soil nutrients are also determined. Intercropping with the green manures Medicago sativa, Trifolium repens, and Dactylis glomerata decreased content of soil available potassium. Trifolium repens increased the content of soil water by 5.71%, and D. glomerata increased the soil pH. Medicago sativa and T. repens increased the soil fungal richness of apple orchard. The dominated soil fungi included Ascomycota, Basidiomycota, Mortierellomycota, and Chytridiomycota. The relative abundance of Glomeromycota in the treatments in which green manure was intercropped was higher than that of the clean cultivated treatment by 234.37-550.0%. Green manure intercropping increased the accumulation of specific genera, such as Petriella, Pseudogymnoascus, and Tetracladium, which can inhibit pathogenic fungi in the soil and promote the decomposition of plant leaves. The intercropping with three green manure crops reduced the content of available potassium in the soil, changed the water content, soil pH, and fungal communities of apple orchards in the Loess Plateau, and aided in the optimization of soil fungal community composition to nutrients uptake and pathogen inhibition.